Changeset 251556 in webkit for trunk/Source/JavaScriptCore/llint/LowLevelInterpreter.asm

Timestamp:

Oct 24, 2019, 1:27:38 PM (6 years ago)

Author:

[email protected]

Message:

[JSC] Remove LLInt's Callee size assumption
​https://bugs.webkit.org/show_bug.cgi?id=203282

Reviewed by Mark Lam.

LLInt code still assumes that Callee is always allocated in non-LargeAllocation.
This patch removes this assumption by following three changes.

1. If we can get CodeBlock, we get VM& from CodeBlock.
2. In nativeCallTrampoline and internalFunctionCallTrampoline, we get VM& from JSGlobalObject. It involves one more pointer-chasing but it is OK since this JSGlobalObject's VM* field will be touched in called native functions anyway. And this code is only used when we are not using JIT.
3. In exception handling code in LLInt, we get VM& from callee by checking LargeAllocation possibility. This is OK since it is only executed when exception unwinding happens, and which is an expensive operation anyway.

• heap/LargeAllocation.h:

(JSC::LargeAllocation::headerSize):

• heap/WeakSet.h:

(JSC::WeakSet::WeakSet):
(JSC::WeakSet::vm const):

• llint/LowLevelInterpreter.asm:
• llint/LowLevelInterpreter32_64.asm:
• llint/LowLevelInterpreter64.asm:
• runtime/JSGlobalObject.cpp:

(JSC::JSGlobalObject::JSGlobalObject):
(JSC::JSGlobalObject::init):

• runtime/JSGlobalObject.h:

(JSC::JSGlobalObject::vm const):
(JSC::JSGlobalObject::defaultCodeGenerationMode const):

• runtime/VM.h:

(JSC::WeakSet::heap const):

File:

• trunk/Source/JavaScriptCore/llint/LowLevelInterpreter.asm (modified) (3 diffs)

trunk/Source/JavaScriptCore/llint/LowLevelInterpreter.asm

@@ -540 +540 @@
 const MarkedBlockMask = ~(MarkedBlockSize - 1)
 const MarkedBlockFooterOffset = constexpr MarkedBlock::offsetOfFooter
+const LargeAllocationHeaderSize = constexpr (LargeAllocation::headerSize())
+const LargeAllocationVMOffset = (LargeAllocation::m_weakSet + WeakSet::m_vm - LargeAllocationHeaderSize)
 
 const BlackThreshold = constexpr blackThreshold
@@ -1129 +1131 @@
 macro notFunctionCodeBlockSetter(sourceRegister)
     # Nothing to do!
+end
+
+macro convertCalleeToVM(callee)
+    btpnz callee, (constexpr LargeAllocation::halfAlignment), .largeAllocation
+    andp MarkedBlockMask, callee
+    loadp MarkedBlockFooterOffset + MarkedBlock::Footer::m_vm[callee], callee
+    jmp .done
+.largeAllocation:
+    loadp LargeAllocationVMOffset[callee], callee
+.done:
 end
 
@@ -1783 +1795 @@
 macro doCallVarargs(opcodeName, size, opcodeStruct, dispatch, frameSlowPath, slowPath, prepareCall)
     callSlowPath(frameSlowPath)
-    branchIfException(_llint_throw_from_slow_path_trampoline)
+    loadp CodeBlock[cfr], t3
+    loadp CodeBlock::m_vm[t3], t3
+    btpz VM::m_exception[t3], .noException
+    jmp _llint_throw_from_slow_path_trampoline
+.noException:
     # calleeFrame in r1
     if JSVALUE64